Note: Descriptions are shown in the official language in which they were submitted.
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A METHOD OF LUBRICATING A CONVEYOR BELT
Description
[0001] The present invention relates to a method of lubricating a conveyor
belt wherein a
lubricant concentrate containing at least one fatty acid is employed in a dry
lubrication
process at a pH-value of < 4. Afterwards, a liquid composition having a pH-
value > 5 is
applied to the surface of the conveyor belt on which the lubricant concentrate
has been
applied earlier.
[00021 Known conveyor belt lubricants are employed in applications in which
good
gliding contact between solid surfaces, for instance glass and metal, or
plastic and metal must
be ensured. These applications include bottle filling and conveying plants,
where the
lubricants are applied to the conveyor belts to ensure the trouble-free
conveyance of bottles
on the belt. In many known systems, a soap such as potash-based (potassium
based) soft soap
is used as the lubricant. The soaps are usually produced from an acidic educt
such as a fatty
acid and a basic educt such as alkanol amines or alkaline hydroxides. Such
soap-based
lubricants are usually in the alkaline pH-range of about 8 to 12 and are
disclosed, for
example, in US-A 5,391,308, US-A 4,274,973 or US-A 3,336,225.
100031 As a substitute for the soap-based lubricants, a variety of synthetic
conveyor belt
lubricants including certain amine compounds are being used. These synthetic
lubricants have
been described in, for example, EP-A-i6 690920, which discloses a lubricant
concentrate
containing a phosphate tri-ester. Said lubricant concentrate contains as
further components an
amine and an acid which may be an inorganic acid such as hydrochloric acid,
nitric acid or
phosphoric acid or an organic acid such as formic acid, acetic acid or oleic
acid. Due to the
presence of the amine, the pH-value of the respective lubricant is usually in
a range of 6 to
12. By consequence, the respective lubricant does not contain the employed
acid in its free
form.
[0004] These conveyor belt lubricants are generally supplied as concentrates.
Use
concentrations (or use solutions) of such concentrates are usually prepared by
applying
typical dilution rates of 0.2-1.0% by weight of the respective concentrate in
water depending
on the friction requirement and the water type. Such aqueous belt lubricants
(aqueous use
solution) having a use concentrate of the active lubricating ingredients of
significantly less
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than 0.1 % by weight have been satisfactorily applied for many years. Such
aqueous use
solutions are also known as "wet lubricants".
10005] WO 01/23504 relates to such a wet lubrication process, wherein an
antimicrobial
lubricant composition is used to treat or lubricate containers and/or conveyor
systems for
containers. The employed lubricant composition comprises a lubricating agent
and an
antimicrobially effective amount of a quaternary phosphonium compound. The
lubricant
agent comprises a non-neutralized fatty acid, which may be oleic acid.
[0006] US-A 2004/0 102 334 relates to a lubricant concentrate comprising a
fatty acid and
a neutralisation agent such as alkaline metal hydroxide, urea or alkyl amines.
The lubricant
additionally contains a pH-buffer for providing a pH-value between 5 and 9.
[0007] US-B 6,288,012 relates to a non-aqueous lubricant for lubrication of
containers
and conveyor systems, whereby the substantially non-aqueous lubricant can
include natural
lubricants, petroleum lubricants, synthetic oils, greases and solid
lubricants.
[0008] US-A 4,420,518 relates to a composition for coating returnable glass
bottles
comprising among others 0-50 wt.-% of a fatty carboxylic acid, for example
mixtures of
Tong-chain carboxylic acids. However, said composition is employed for coating
glass bottles
instead of lubricating a conveyor belt.
[0009] US-A 2005/0 288 191 relates to a conveyor lubricant composition
comprising at
least one lubricant and at least one protectant for PET bottles such as alkyl
ether carboxylic
acid or salts thereof. The lubricant employed may be any lubricant known to a
skilled person
including fatty acids (such as oleic acid) or alkanol amines.
[00010] EP-A 1 840 196 relates to a lubricant composition for conveyor
systems.
comprising phosphoric acid esters, ether carboxylates, water and C6-C22 fatty
acid, such as
oleic acids, and/or C6-C22 fatty alcohols.
[00011] Kao Chemicals GmbH (Emmerich, Germany) offers a lubricant concentrate
under
the trade name AKYPO GENE CL 756 which contains - among others - fatty acids
(approx.
wt.-I/o) and which is amine-free. Kao also suggests a method of employing said
lubricant
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concentrate as a wet lubricant, wherein the concentrate is diluted to conveyer
belt lubricants
with concentrations between 8 to 11 % to form an aqueous emulsion. Said
diluted conveyor
belt lubricant is farther diluted with water to 0.2-0.4% (aqueous use
solution) to be finally
applied on the conveyor belt as a wet lubricant.
[00012] US-A 5,723,418 relates to a lubricant concentrate composition
containing an
effective lubricating amount of an amine, a corrosion inhibitor and a
surfactant. A fatty acid
may be added to said composition as a neutralizing agent for obtaining a pH-
value ranging
from about 5-10.
[00013] US-A 5,399,274 relates to a lubricant composition for use in metal-
working
processes comprising a fatty acid, an amino alcohol and a phosphate ester. The
fatty acids
employed are neutralized with an amino alcohol and complexed with an organic
phosphate
ester for obtaining a pH of the lubricant of at least about 8. The lubricant
is useful in sizing,
coining and machining of powdered metal parts and/or conventional ferrous and
non-ferrous
metal parts.
[00014] US-A 2004/0 241 309 relates to an improved food-grade lubricant
useful, for
example, as hydraulic oil or compressor oil. The lubricant comprises at least
one vegetable
oil, at least one polyalphaolefin and at least one- antioxidant.
[00015] US-A 4,839,067 relates to a process for lubrication and cleaning of
bottle
conveyor belts without the formation of tenacious deposits and objectionable
odours as when
using potash-based soaps as wet lubricant. The process comprises a first step
of applying a
lubricant comprising a base of neutralized primary fatty amines on the
conveyor belt. The
lubricant can be neutralized to a pH-value of 6-8 with acetic acid. In a
second step, the
conveyor belt is cleaned with at least one cleaning agent selected from
cationic cleaning
agents (for example, quaternary ammonium compounds such as alkyl dimethyl
benzyl
ammonium) and an organic acid. It is indicated that said cleaning step can be
carried out once
in a while, for example, daily or weekly. However, the removal of dirt or
deposits from a
conveyor belt is usually already performed by the wet lubrication process
itself (such as the
first step of the method described in US-A 4,839,067), since most of the
employed lubricant
(use solution) drops off from the surface of the respective conveyor belt. The
off-dropping
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(off-flowing) liquid usually takes away most of the dirt or deposits from the
surface of the
conveyor belt.
[00016) However, none of the above-described (mostly aqueous) lubricants are
employed
in a dry lubrication process. Most of them are employed as use solutions and
therefore as wet
lubricants, some of them are even used in different applications such as
hydraulic oils. Most
of them may contain a fatty acid such as oleic acid as an optional or even a
mandatory
component, but the fatty acid is usually present in its neutralized form due
to additional
components such as neutralizers, amines or any other components causing a pH-
value in the
neutral or alkaline range.
[00017] On the other hand, the application of these aqueous lubricants (wet
lubricants) has
also resulted in high water usage rates and relatively high effluent costs for
the user.
Furthermore, when used as conventionally intended these aqueous lubricants
flow off the
conveyor track surface treated therewith, resulting in a waste of chemical and
water, and
causing a slippery floor surface which may constitute a hazard to operators
working in the
immediate environment and collecting on.floors and other surfaces which then
requires
cleaning.
100018] In order to overcome the before-mentioned disadvantages of employing
wet
lubricants, WO 01/07544 discloses the use of a liquid composition for
lubricating conveyor
belts as a so-called "dry-lubricant". The liquid composition is suitable for
producing a dry
lubricant film which remains on the surface of the respective conveyor belt
onto which it is
applied (as a liquid) and which consequently does not flow off from said
surface. The liquid
is usually an aqueous phase (up to 95% by weight of water) and further
comprises a silicone
oil or other oils selected from vegetable oils, mineral oils and mixtures
thereof. Vegetable oils
may be soy oil, palm oil, olive oil or sunflower oil. The liquid composition
is suitable for
continuous application to the conveyor belt surface, with or without further
dilution with
water, to remove incidental spillages of extraneous material from the conveyor
belt surface
without loss of the required lubricity. According to the working examples of
WO 01/07577,
the conveyor belts are sprayed with water after a certain time of operation
under dry
lubrication conditions.
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[00019] The international application PCT/US 2007/087143 relates to a method
of
lubricating a conveyor belt wherein the lubricant concentrate is employed as a
dry lubricant
in a dry lubrication process. The lubricant concentrate contains at least 0.1
wt.-% of at least
one free fatty acid and at least one corrosion inhibitor.
[00020] US-A 200510 059 564 relates to a composition and method of lubricating
conveyor tracks or belts wherein the lubricant composition contains at least
about 25 wt.-%
of fatty acid. The lubrication process may optionally be carried out as a dry
lubrication. In
one embodiment, the fatty acid may be present in its free form. However, the
lubricant
composition requires the presence of mandatory components such as neutralizers
or
polyalkylene glycol polymers. Since neutralizers components such as amines or
alkaline
metal hydroxides are employed a rise of the respective pH-value to the neutral
or alkaline
range is caused. By consequence, the respective lubricant is not employed in
the acidic range
and it does not contain any fatty acid in its free form. A similar disclosure
to US-A 2005/0
059 564 can be found in US-B 6,855,676.
[00021] US-B 6,427,826, US-B 6,673,753 and EP-A 1 308 393 relate.to. further
lubrication
methods, which may optionally be carried out as a dry lubrication. Various
types of lubricants
may be employed such as lubricants based on water-miscible silicon material or
mineral oils.
The lubricants may additionally contain fatty acids such as oleic acid. In EPA
1 308393, it is
further indicated that a container or conveyor belt may optionally be cleaned
from a silicon-
based lubricant by treatment with water or using common or modified detergents
including,
for example, one or more surfactants, an alkalinity source or water-
conditioning agents.
[00022] However, nowhere within said documents describing a dry lubrication
process as
an optional form of lubricating a conveyor belt, a method is disclosed wherein
a dry
lubrication with a fatty acid is carried out in the acidic range followed by
the application of a
liquid composition containing a base and a fatty acid and having a pH-value of
> 5.
[00023] One major advantage of the method of dry lubrication versus wet
lubrication is the
drastic reduction in the volumina of the respective liquid, which is employed
for lubrication.
In an ordinary dry lubrication of a conveyor belt, approximately 1.5 to 20
ml/h of the
respective lubricant are applied on the conveyor belt (as dry lubricant),
whereas in case of
wet lubrication, approximately 10-301/h of an aqueous solution have to be
applied on the
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same conveyor belt. The voluminas of the respective liquid lubricants to be
employed on the
conveyor belt usually differ by the factor of 1000 to 10000 (wet lubrication
versus dry
lubrication).
[00024] However, the method of dry lubrication as described, for example, in
WO
01/07544 is also associated with some disadvantages. Especially due to the
employment of
dry lubricants containing vegetable oils or, in particular, mineral oils, a so-
called blackening
is observed on the bottom surface of the containers to be transported on the
conveyor belt.
This blackening is often caused by dirt usually attached to the container
surface, especially in
case of the transportation/re-filling of used containers or by wear of, for
example, glass or
metal originating from the objects to be transported on the conveyor belt. A
further source of
dirt on the conveyor belt are fractions of liquids such as beer or sugar-
containing beverages,
which have not been filled into the container during the respective (re-
)filling process but
have flown down on the outer surface of the respective container onto the
conveyor belt. The
blackening problem usually occurs only in the case of a dry lubrication
process, but not
during a wet lubrication process, since most of the dirt is carried away from
the surface of the
conveyor belt by the lubricant use solution flowing off.
[00025] Since it is difficult to remove said mixture of dirt and vegetable oil
or especially
mineral oil from the conveyor belt to avoid blackening, the whole conveyor
belt system has
to be stopped from time to time to perform an additional cleaning step. This
cleaning is
usually performed by employing strong akaline detergent compositions
containing surfactants
because the oil-dirt-mixtures, especially when employing mineral oils, can
only be
insufficiently removed by ordinary aqueous detergent compositions. If the used
up lubricant
film is not completely removed from the conveyor belt, the blackening problem
is not solved.
In addition, the new lubricant film is formed incompletely causing problems in
respect of the
objects to be transported. After the cleaning, further time has to be spent to
sufficiently (re-
)apply the lubricant on the respective conveyor belt (so-called starting
phase) until the whole
system can be operated without any problems in respect of the transportation
of the
containers.
[00026] Therefore, the object of the present invention is to provide a new
method of dry
lubrication for a conveyor belt.
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[00027] The object is achieved by a method of lubricating a conveyor belt,
comprising the
steps as follows:
[00028] a) a lubricant concentrate containing at least one fatty acid is
employed in a
dry lubrication process, wherein the pH-value of the lubricant concentrate
is in the range of < 4,
[00029] b) afterwards, a liquid composition is applied to the surface of the
conveyor belt,
wherein
the pH-value of the liquid composition is in a range of > 5
the liquid composition contains as component a) at least one base and
the liquid composition contains as component b) at least one fatty acid.
[00030] A major advantage of the method according to the present invention is
that
excellent lubricity is provided on the conveyor belts (due to low friction)
during the dry
lubrication process (step a). The dry lubrication process according to step a)
of the present
invention provides improved lubricity compared to dry lubrication processes
employing
different types of lubricant concentrates or compared to the corresponding wet
lubrication
processes. In addition, the power consumption of the engines of the conveyor
belts can he
reduced by-l0 to 20% at a dry lubrication process compared to the
corresponding wet
lubrication process.
[00031] Due to step b) according to the method of the present invention, the
dirt attached
to the surface of the conveyor belt (causing the blackening on the bottom
surface of the
containers to be transported) can be easily removed. Therefore, step b) has to
be considered
as a cleaning (washing) step on the one hand. This washing is very effective,
since the dry
lubricant (fatty acid) and the base component of the liquid composition of
step b) build up a
soap. Whereas the base itself has no or only very limited lubrication
properties, the soap
made of the lubricant from the conveyor belt and the base contained in the
liquid composition
have excellent lubrication properties. By consequence, step b) can also be
considered as a
combined washing and lubrication step. The soap can be considered either as a
chemical
reaction product or an adduct of the base and the fatty acid. This effect
cannot be observed
when employing for example a mineral oil as a dry lubricant.
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[00032] Since the liquid composition employed in step b) does not only contain
a base as a
component, but also at least one fatty acid as an additional component, there
is always a
supply of fresh soap from the liquid composition to the conveyor belt surface
as long as step
b) is carried out. This is a big advantage, since the soap does not only
effect a fast removal of
the dirt and the incomplete or damaged dry lubrication film from the conveyor
belt, but it
additionally provides continued lubrication on the conveyor belt. The removal
of the dirt
from the conveyor belt surface occurs faster if the liquid composition
contains a molar excess
of base versus fatty acid. By consequence, excellent lubricity is maintained
during the
subsequent cleaning (washing) step b). This means that the operation of the
conveyor belt
does not have to be interrupted at all when effectively removing dirt from the
conveyor belt
to avoid the blackening of the containers to be transported. Therefore, such a
conveyor belt
can be operated in a 24/7-operation mode (7 days a week for 24 hours each).
[00033] Since the cleaning due to step b) is very effective, step b) does not
have to be
carried out for a very long time. It is very easy to switch back to the dry
lubrication according
to step a). This is also advantageous, since step a) is carried out in the
acidic pH-range
reducing the problems associated with lime soap formation and the growing of
bacteria (see
below). As indicated above, the dry lubrication process is also favourable in
respect of the
lubricity.
[00034] In contrast to dry lubricants based on oils, especially on mineral
oils, the lubricant
concentrates containing fatty acids according to the present invention show a
superior
compatibility with water, especially when employed as an emulsion containing
the fatty acid,
water and an emulsifier or when employed as a solution of the fatty acid in an
organic
solvent.
[00035] Another advantage of the method according to the present invention is
that in
those embodiments, where in step a) a lubricant concentrate is employed
containing a fatty
acid and a corrosion inhibitor, the corrosion of the conveyor belt, further
conveyor equipment
and/or the object to be transported can be reduced. This is for example the
case when objects
made of tin plate are transported on a conveyor belt, even if the conveyor
belt is made from
stainless steel. The combination of a fatty acid and a corrosion inhibitor has
the additional
effect of a reduced blackening on the objects to be transported.
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[00036] The method according to the present invention provides excellent
lubricity
independent of the kind/quality of the object to be transported or the
material of the conveyor
belt. The objects to be transported may be partially or completely made of
glass, metal,
carton, or plastics and the conveyor belt may be partially or completely made
of steel or
plastic. The method according to the present invention provides excellent
lubricity for the
transportation of, for example, glass bottles on stainless steel conveyor
belts. The
transportation of objects to be filled and in particular to be refilled on
conveyor belts, where
neither the object to be transported nor the conveyor belt itself is partially
or
completely made of plastics, has been quite complicated so far. The method
according to
the present invention provides improved lubricity for the transportation of
used objects
made of glass on stainless steel conveyor belts.
[00037] The lubricant concentrate containing the fatty acid has a pH-value of
< 4,
preferably in the range of pH 1-3. This is an advantage, since many lubricant
concentrates
according to the state of the art (or the respective use solution thereof) are
in the neutral or
alkaline range. Such lubricant concentrates usually contain further additives
such as
neutralizers (amines or alkaline hydroxides), chelating agents such as EDTA,
polymers such
as polyalkylene glycol, mineral oils such as silicon-based oils which
optionally may be
fluorinated or (water-miscible) silicone materials. The lubricant concentrates
employed
within the method according to the present invention do not need to contain
the before
mentioned additives as further components, since they are also associated with
disadvantages.
[00038] Chelating agents such as EDTA are used to prevent lime soap formation
on the
conveyor belt. The formation of lime soap on a conveyor belt normally occurs
by employing
neutral to alkaline lubrication conditions. The lime soap formation has the
negative side
effect that it drastically reduces or even stops the lubrication on the
respective conveyor belt.
The employment of chelating agents such as EDTA has the negative side effect
that they are
not readily biodegradable. Since the lubricant concentrates employed in step
a) of the present
invention are in the acidic range of the pH-spectrum, no formation of lime
soap occurs. In
addition, the rather low pH-range of the lubricant concentrate provokes a
biostatic effect and
no growing of bacteria or food and/or beverage parasites occurs. A further
stabilization of the
respective lubricant concentrate is obtained when employing another acid
besides the fatty
acid, such as acetic acid.
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[000391 It is usually avoided using (water-miscible) silicon materials as
those disclosed in
EP-A 1 308 393 as a component of a lubricant for conveyor belt system,
especially in
connection with the (re-) filling and/or washing of glass bottles. Those
(water-miscible)
silicon materials including silicon-based oils have the negative side effect
of strongly
adhering to objects made of glass. During the washing step of said objects, a
considerable
amount of said material is removed from the bottom surface of the respective
object by the
washing liquid (usually an aqueous liquid) employed. Since the objects to be
washed are
usually entirely put into the respective washing liquid, the silicon material
is also transported
to the interior of said object. Like from the outside of said object, it is
also rather difficult to
completely remove the silicon material from the inside of the respective
object. The silicon
material attached to the inside of an object (bottle) made of glass causes a
bad taste of, for
example, a beer to be filled into said bottle. Furthermore, the silicon
material has a very
negative effect on the foaming stability of beer. If a beer is poured into a
glass out of a bottle
containing silicon material in its interior, the respective beer does not show
any or only a very
limited foaming behavior. However, most customers expect to consume a beer
with foam as a
sign of good and fresh quality.
[00040] A further advantage is that the lubricant concentrate employed in step
a)
containing at least one fatty acid can be used both as dry lubricant and as
wet lubricant. This
allows a combination of both methods on the same conveyor belt system. For
example, the
refilling of a used glass container consists of several individual steps,
whereby said glass
container is transported on a conveyor belt to individual sections integrated
into the conveyor
belt to carry out the individual steps (sections such as bottle washing,
filling or labelling). It is
therefore possible to carry out some of the individual steps employing a dry
lubricant, and
during one or more of the individual steps a wet lubricant is employed.
Alternatively, the
lubrication of parts or the entire conveyor belt can be carried out as wet
lubrication for certain
time intervals (temporarily). If demanded by the customer, the operation of
the whole system
can be continued by simply switching the mode of lubrication from dry
lubrication to wet
lubrication and vice versa.
[00041] The term "dry lubricant" in connection with the present invention
means that the
employed lubricant is applied on the respective conveyor belt (in step a) in a
way that the
respective lubricant remains on the surface of said conveyor belt either
completely or at least
substantially. Remaining substantially means that not more than 10% by volume
of the
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employed lubricant are flown off (dropped off) the respective conveyor belt.
For the sake of
clarity, it is indicated that the dry lubricant itself is usually employed as
a liquid, for example,
as an emulsion or a solution. The process (method) connected with the
application of said dry
lubricant is defined as "dry lubrication (process)". Preferably, the lubricant
concentrate is
added within a dry-lubrication process according to the present invention at a
ratio of 1.5 to
20 ml/h in particular about 5 ml/hour, on the respective conveyor belt (per
conveyor belt
track depending on ordinary size of 5 - 20 m, preferably about 12 m).
[00042] The term "wet lubricant" in connection with the present invention
means that the
respective lubricant is applied onto the surface of a conveyor belt in a way
that a
significant amount of the lubricant employed or the liquid containing the
lubricant flows
off from the surface of the respective conveyor belt. The process (method)
connected with the
application of said wet lubricant is defined as "wet lubrication (process)".
Preferably, at least
30% of volume of the employed amount of liquid flows off, more preferably at
least 50% by
volume, in particular at least 90% by volume. Preferably, the lubricant is
added within a wet
lubrication process at a ratio of 1.5 to 20 1/hour on the respective conveyor
belt (per conveyor
belt track/ordinary size of 5 - 20 in, preferably about 12 m).
[00043] The term "lubricant concentrate" in connection with the present
invention means
that the respective lubricant contains one fatty acid or a mixture of two or
more fatty acids,
preferably in an amount of at least 0.1 wt.-%. The lubricant concentrate may
contain further
components including at least one corrosion inhibitor, water or organic
solvents, resulting in
a total of 100 wt.-% (sum of fatty acids and further components).
[00044] The term "use solution (of a lubricant)" in connection with the
present invention
means that the amount of one fatty acid or a mixture of two or more fatty
acids contained
within the respective lubricant is preferably below 0.1 wt.-%, more preferably
below 0.01
wt.-%. Usually a use solution of a lubricant is obtained by diluting the
respective lubricant
concentrate with a solvent, preferably with water, by a factor of 1000 to
10000.
[00045] It has to be indicated that in the present invention chemical
compounds are
mentioned by their chemical structure/name in the respective pure form (before
mixing them
with other compounds) unless indicated otherwise. Especially when they are
employed in a
mixture their chemical structure may be altered due to the influence of, for
example, the pH-
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value of the respective mixture. For example, a fatty acid may completely or
partially be
present in its free (usually protonated) form. This is usually the case in the
acidic pH-range,
for example, at a pH-value of < 4. However, a fatty acid may also be
completely or partially
present in its unprotonated form. This is usually the case in the neutral or
alkaline pH range,
where the fatty acid is completely or partially transferred into a
corresponding salt or a
chemical reaction may take place.
[00046] Subsequently, the method of lubricating a conveyor belt according to
the present
invention is explained in detail.
[00047] Ste a :
[00048] The lubricant concentrate employed as dry lubricant (in a dry
lubrication process)
contains as a first component at least one fatty acid. The fatty acid may be
any fatty acid
known to the skilled person. Preferably, the fatty acid is a C8-C22-fatty acid
such as capric
acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid or
linoleic acid. The fatty
acid may be a saturated fatty acid, a mono-unsaturated fatty acid or a
polyunsaturated fatty
acid. Preferably, the respective acid is completely or partially employed as a
free fatty acid.
[00049] Most preferably, the fatty acid is oleic acid.
[00050] The term "free fatty acid" in connection with the present invention
means that the
acidic functional group (carboxylic group) of the respective fatty acid is not
blocked by or
reacts with any other component of the respective lubricant. Preferably, the
respective
lubricant does not contain any counter ions which may block and/or react with
the carboxylic
group of the respective fatty acid. In particular, the respective lubricant
does substantially not
contain any cationic ions or other cationic components which may act as a
counter ion of the
carboxylic group. In addition, the respective lubricant concentrate is
preferably free of any
amines.
[00051] If the lubricant concentrate contains any other components, which may
block or
react with the acidic functional group of the employed (free) fatty acid, the
amount of fatty
acid employed in the lubricant concentrate according to the present invention
has to be raised
to a level, which effects a concentration of preferably at least 0.1 wt.-% of
(free) fatty acid.
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Methods for detection of the amount of the (free) fatty acids contained in a
composition, such
as a lubricant concentrate, are known in the art.
[00052] The lubricant concentrate generally contains at least one fatty acid
or a mixture of
two or more fatty acids in an amount of at least 0.1 wt-%, preferably in an
amount of 0.1 to
25 wt-%, more preferably in an amount of 0.3 to 5 wt.-%.
[00053] The lubricant concentrate employed in the dry lubrication process
according to
step a) the present invention has a pH-value in the range of < 4, preferably
in the range of < 3,
more preferably of 1-3, in particular of (about) 2. If the lubricant
concentrate is further
diluted, for example, if a dry lubrication process is combined with a wet
lubrication process,
then the use solution (lubricant concentrate diluted with, for example, water)
usually has a
pH-value in the range of 5.5 to 7.5, preferably 7.
[00054] In one embodiment of the present invention a lubricant concentrate is
employed
containing 0.1 to 25 wt-% of at least one fatty acid and 5 to 95 wt.% of
water, preferably
deionised water, and optionally at least 0.1 wt.-% of a corrosion inhibitor.
[00055] The lubricant concentrate may contain as a further component at least
one
corrosion inhibitor. Preferred corrosion inhibitors are phosphoric acid esters
(phosphate
esters), which may contain fragments derived from ethylene oxide (EO) such as
oleyl-3EO-
phosphate esters.
[00056] In general the phosphate ester has the formula OP(OX)3 where X is
independently
H or R and R may represent an aryl or alkyl group. Preferably, the phosphate
ester is at least
one compound having the formulae (I) or (II)
CA 02719568 2010-09-23
WO 2009/120751 14 PCT/US2009/038196
RO(GH2CH20 0
/P
RO(CH2CH2O)r, SOH
or
RO(CH2CH2O). 0
~
(11)
P
HOB `OH
[00057] where R is an alkyl or alkylaryl group; n can (independently from
another) equal
from 1 to 10. Within formulae (1) or (II), R may have the same or a different
meaning, if R is
present more than once. Preferably, the phosphate esters do not contain any
ions such as Na
or K. Alkyl may be for example Cl-C2D-alkyl, aryl may be phenyl. In one
embodiment of the
present invention, a mixture of at least one compound of formula (I/diester)
and at least one
compound of formula (II/monoester) is employed. The ratio of diester to
monoester within
said mixture is from 1:4 to 4:1 [wt.-%/wt.-%], preferably about 1:1 [wt.-
%/wt.%]. In a
preferred embodiment of the present invention, the phosphate ester is at least
one diester
according to formula (I). The diester may contain up to 10 wt.-% of the
respective monoester
(as a by-product).
[00058] Preferred examples of phosphate esters according to formulae (I) or
(II) are
(C16-C1$)-alkyl-O-5EO-phosphate ester (mixture of mono- and diestester),
(cetyl-oleyl)-O-
4E0-phospate ester (mixture of monoester and diester), (C12-C14)-alkyl-O-4EO-
phosphaete
ester (mixture of monoester and diester), (C13-C15)-alkyI-O-3EO-phosphate (C13-
Cis)-alkyl-
O-7E0-phosphate ester, oleyl-O-4EO-phosphate ester (mixture of monoester and
diester),
lauryl-O-4EO-phosphate ester and C17-alkyl-O-6EO-phosphate ester (mixture of
mono- and
diester, preferably in a ratio of 5.5 : 4.5). Within said phosphate esters, a
term such as
"(C16-C18)" means that the respective alkyl residue may vary in its chain
length from
C16 to C18 or a mixture of said alkyl residues of the respective chain length
are employed.
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WO 2009/120751 15 PCT/US2009/038196
The same applies to terms such as "(cetyl-oleyl)". Said preferred phosphate
esters are
commercially available under the tradenames Phospholan PE 65 (Akzo Nobel),
Maphos 54P
(BASF), Maphos 74P (BASF), Maphos 43T (BASF), Maphos 47T (BASF), Lubrhophos LB-
400 (Rhodia), Lubrhophos RD-510 (Rhodia) and Lakeland PAE 176 (Lakeland). More
preferably, the phosphate esters according to formula (I) or (II) contain a
(C12-C I g)-alkyl
fragment and 3 to 6 EO-fragments.
[00059] A further class of preferred corrosion inhibitors are alkoxylated
carboxylic acids,
which are also known as alkylethercarboxylic acids and are saturated or
unsaturated
carboxylic acids containing one or more ether groups or mixtures thereof.
Alkoxylated is
preferably ethoxylated and means that the respective ethoxylated compound
contains one or
more fragments derived from ethylene oxide (EO-fragment). 3EO means that the
respective
compound contains 3 fragments derived from ethylene oxide. This definition
also applies to
the below or above mentioned compounds such as akoxylated fatty alcohols,
alkoxylated
esters or alkoxylated phosphate esters.
[00060] Preferred ethoxylated carboxylic acids contain a C4-C18-alkyl fragment
and 1 to 6,
preferably 3 to 6, EO-fragments. C4-CIR-alkyl means that the respective
fragment contains
from 4 up to 18 carbon atoms, which form an alkyl residue or a mixture of the
at least two
alkyl residues within the indicated range is employed. Usually, ethoxylated
carboxylic acids
are employed as mixtures of two more acids, such as (C16-C18)-akylethecr
arboxylic acid.
Preferred examples of ethoxylated carboxylic acids are C12-alkyl-4EO-
carboxylic acid, (C16-
C18)-alkyl-2EO-carboxylic acid, (C16-C18)-alkyl-5EO-carboxylic acid, (C16-C18)-
alkyl-
10,5EO-carboxylic acid or (C4-C8)-alkyl-8E0-carboxylic acid. More preferably,
the
ethoxylated carboxylic acid is C12-alkyl-4EO-carboxylic acid. Ethoxylated
carboxylic acids
are commercially available, for example, from Kao Chemicals GmbH (Emmerich,
Germany)
under the trade names Akypo RLM 25, Akypo RO 20, Akypo RO 50, Akypo RO 90,
Akypo
RCO 105 or Akypo LF2. In one preferred embodiment of the present invention,
the
ethoxylated carboxylic esters contain a (C12-C1S)-allkyl-fragment and 3 to 6
EO-fragments.
Examples are C12-alkyl-4EO-carhoxylic acid, or (C16-C18)-alkyl-5EO-carboxylic
acid.
[00061] In one embodiment of the present invention, the corrosion inhibitor is
at least one
phosphate ester and at least one alkoxylated carboxylic acid- In another
embodiment of the
present inv6ntion, the corrosion inhibitor is at least one phosphate ester. In
a further
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WO 2009/120751 16 PCT/US2009/038196
embodiment of the present invention, the corrosion inhibitor is at least one
alkoxylated
carboxylic acid.
[00062] The presence of a corrosion inhibitor within the lubricant concentrate
employed in
the present invention is connected with the advantages of providing anti-
corrosive properties,
emulsifying effects, lowering the pH-value to a range of < 4, preferably I to
3 and also
reducing the blackening during a dry lubrication process.
[00063] If present, the lubricant concentrate generally contains at least one
corrosion
inhibitor in an amount of at least 0.1 wt-%, preferably in an amount of 0.1 to
25 wt.-%, more
preferred in an amount of 0.1 to 9.0 wt.-%.
[00064] Besides the fatty acid, optionally the corrosion inhibitor and
optionally water, the
lubricant concentrate may contain one or more further components known by a
skilled person
such as surfactants, emulsifiers, acids such as strong or weak organic acids,
for example,
saturated or unsaturated carboxylic acids containing one or more ether groups,
solvents, or
fatty alcohols. The optional components as well as the corrosion inhibitor are
chosen in a way
that they do not hinder the free availability of the carboxylic group of the
(free) fatty acid.
The optional components are also chosen in a way that they are compatible with
each other,
for example, in respect of their miscibility.
[00065] Examples for suitable surfactants can be found in WO 01/07544 or US-B
6,427,826. Preferred surfactants include alkylbenzenesulfonic acid, carboxylic
acids,
allcylphosphonic acids and their calcium, sodium and magnesium salts,
polybutenylsuccinic
acid derivatives, silicone surfactants, fluorosurfactants, and molecules
containing polar
groups attached to an oil-solubilizing aliphatic hydrocarbon chain. If stable
and existing, the
above indicated preferred surfactants are employed in their acidic form and
not as salts. The
surfactants are used in an amount to give desired results. This amount can
range from 0 to
about 30, preferably about 0.5 to about 20 wt.-% for the individual component,
based on the
total weight of the composition.
[00066] Emulsifiers (emulsifying agents) are also known by a skilled person,
they may
comprise compounds, which may also be employed as (organic) solvents or
surfactants-
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Preferred emulsifiers according to the present invention are alkoxylated fatty
alcohols,
alkoxylated esters, fatty alcohols or phosphate esters which are optionally
alkoxylated.
[00067] Preferred fatty alcohols are cetyl alcohol or oleyl alcohol, in
particular cetyl
alcohol (1-hexadecanol). Alkoxylated fatty alcohols are preferably ethoxylated
fatty alcohols.
Ethoxylated fatty alcohols suitable as emulsifiers are commercially available
from BASF AG
(Ludwigshafen, Germany) under the trade names Lutensol XL-Series (such as XL
70),
Emulan EL, Emulan NP 2080, Emulan OC, Emulan OG, Emulan OP25, or Emulan OU.
Preferred examples of ethoxylated fatty alcohols are RO(C2H4O)xH with R =
C1OH21 and x =
4, 5, 6, 7, 8, 9, 10 and 14.
[00068] Alkoxylated esters are preferably ethoxylated esters. Ethoxylated
esters are esters
of carboxylic acids containing one or more ether groups (EO-fragments) within
the ester
fragment derived from the corresponding alcohol. Preferred ethoxylated esters
are
ethoxylated fatty acid esters, in particular ethoxylated esters of oleic acid,
which is
commercially available from BASF AG under the trade name Emulan A.
[00069] In a preferred embodiment of the present invention, the lubricant
concentrate
employed in step a) further contains at least one acid. This acid does not
fall under the
definitions of a (free) fatty acid as indicated- above. Preferably, this acid
is selected from
strong or weak organic acids, including alkoxylated carboxylic acids.
[00070] More preferably, this acid is a weak organic acid such as propionic,
glycolic,
gluconic, citric, acetic or formic acid, in particular acetic acid. The
presence of said
(additional) acid within the lubricant concentrate effects a better adjustment
of a lower pH-
value of the lubricant concentrate (in the range of < 4), preferably a pH-
value of 1-3, in
particular of (about) 2. If present, the concentration of said (additional)
acid is an amount of
at least 0.1 wt.-%, preferably in an amount of 0.1 to 25%, more preferably 0.1
to 5.0 wt.-%.
[00071] In another embodiment of the present invention, a lubricant
concentrate is
employed containing 0.1 to 25 wt-% of at least one fatty acid, 0.1 to 25 wt.-
%, preferably 0.1
to 9.0 wt.-% of at least one corrosion inhibitor, 0.1 to 25 wt.-%, preferably
01 to 5.0 wt.-% of
at least one acid and 5 to 95 wt-% of water and/or at least one organic
solvent.
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WO 2009/120751 18 PCT/US2009/038196
Preferred organic solvents are glycol ethers, in particular dipropylene
glycolmethyl ether,
which is commercially available under the trade name Dovanol DPM from Dow
Chemicals.
Optionally, mixtures of water and at least one organic solvent may also he
employed. If the
lubricant concentrate contains an organic solvent, preferably more than 10 wt.-
%, said
concentrate is preferably applied onto the conveyor belt as a (clear) solution
and/or
discontinuously.
[00072] In a preferred embodiment of the present invention, a lubricant
concentrate is
employed containing 0.1 to 25 wt.-% of at least one fatty acid, 0 to 95 wt.-%
of water, 0.1 to
95 wt.-% of at least one emulsifier, 0 to 25 wt.-% of at least one acid, 0 to
30 wt.-% of at least
one further component, preferably a surfactant and 0.1 to 25 wt.% of at least
one corrosion
inhibitor. Preferably, the lubricant concentrate is applied onto the conveyor
belt as an
emulsion and/or discontinuously.
[00073] In another preferred embodiment of the present invention, a lubricant
concentrate
is employed wherein the amount of vegetable oils, in particular rapeseed oil,
soy oil, palm oil,
olive oil or sunflower oil, is below 20 wt-%, more preferably below 10 wt.-%,
much more
preferably below 5 wt.-% and most preferably below 1 wt.-%.
[00074] - - - In-one embodiment of the present invention. a-lubricant
concentrate is employed
which does not contain any neutralizer in a substantial amount. In a
substantial amount in
connection with neutralizers as well as the below indicated mineral oils,
(water-miscible)
silicon material, complexing agents or polyalkylene polymers means that the
neutralizer is
not present at all within the employed lubricant concentrate or its
concentration is below an
amount of 0.05 wt.%, preferably 0.01 wt.-% of the lubricant concentrate.
Examples for
neutralizers (neutralizing agents) are alkaline metal hydroxides such as
potassium hydroxides
and sodium hydroxides, ammonia, buffers such as sodium carbonate, potassium
carbonate or
sodium phosphate, alkyl amines, such as primary, secondary, tertiary amines or
alkanol
amines and amines such as fatty alkyl substituted amines.
[00075] In another embodiment of the present invention, a lubricant
concentrate is
employed which does not contain a polyalkylene glycol polymer in a substantial
amount.
Such polyalkylene glycol polymers include polymers of alkylene oxides or
derivatives and
mixtures or combinations - thereof, usually having a molecular weight of at
least 1000 up to
CA 02719568 2010-09-23
WO 2009/120751 19 PCT/US2009/038196
about hundreds of thousands. Such polyalkylene glycol polymers are disclosed,
for example,
in US-B 6,855,676.
[00076] In another embodiment of the present invention, a lubricant
concentrate is
employed, which does not contain chelating agents in a substantial amount. In
particular,
such chelating agents are ethylene diamine tetraacetic acid (EDTA) or salts
thereof, in
particular disodium or tetrasodium salt, iminodisuccinic acid sodium salt,
trans-1,2-
diaminocyclohexane tetracetic acid monohydrate, diethylene triamine pentacetic
acid,
sodium salt of nitrilotriacetic acid, pentasodium salt of N-hydroxyethylene
diamine
triacetic acid, trisodium salt of N,N-dipeta-hydroxyethyl)glycine, or sodium
salt of sodium
glucoheptonate.
[00077] In another embodiment of the present invention, a lubricant
concentrate is
employed, which does not contain any mineral oils in a substantial amount.
Mineral oils
within the present invention comprise also silicon-based oils, fluorinated
oils and fluorinated
greases, available under the trademark "Krytox" from DuPont Chemicals and
other synthetic
oils.
[00078] In another embodiment of the present invention, a lubricant
concentrate is
employed, which does not contain any silicon- material in a substantial
amount. Said silicon
material is usually a water-miscible silicon material. Such silicon material
comprises alkyl
and aryl silicons, functionalized silicons such as chlorosilanes, amino-,
metoxy-, epoxy- and
vinyl substituted siloxanes and silanoles, which may be present as emulsions
or as powders.
Such (water-miscible) silicon materials are disclosed, for example, in EP-A 1
308 393, in
particular in paragraph 48.
[00079] The lubricant concentrate employed in step a) may be prepared as known
in the
art, for example, by mixing the individual components in any order. However,
lubricant
concentrates according to the present invention may also be prepared by
diluting a first
concentrate containing at least one fatty acid (and a corrosion inhibitor)
with a solvent such
as water. The obtained mixture preferably contains at least 0.1 wt.% of at
least one fatty acid
or of a mixture of two or more fatty acids.
CA 02719568 2010-09-23
WO 2009/120751 20 PCT/US2009/038196
[00080] Step b):
[00081] The liquid composition employed in step b) is applied to the surface
of the
conveyor belt. The components contained within said liquid composition may be
any
component under the proviso that the pH-value of the liquid composition is in
the range of
> 5 after the individual components of the respective liquid composition are
mixed together.
[00082] The liquid composition contains as component a) at least one base.
Preferably, the
base is selected from an alkanol amine, an amine, ammonia, ammonia hydroxide,
urea, an
alkaline hydroxide, a buffer, a fatty amine, an alkoxylated fatty amine, a
fatty amine oxide or
an alkoxylated fatty amine oxide.
[00083] The alkonol amine is preferably an ethanol amine, more preferably
monoethanol
amine (MEA), diethan of amine (DEA) or triethanol amine (TEA). An alkaline
hydroxide
(alkaline metal hydroxide) is preferably potassium hydroxide or sodium
hydroxide, more
preferably potassium hydroxide. Ammonia (NH3) and ammonia hydroxide (NH4OH)
are
usually employed as an aqueous liquid. Besides urea, any stable derivative of
urea known to a
person skilled in the art may also be employed as a base.
[00084] The term amine comprises any amine different to the above-defined
alkanol
amines or the below indicated fatty amines, alkoxylated fatty-amines or the
respective amine
oxides thereof. An amine may be, for example, a primary, secondary or tertiary
alkyl amine,
or a cyclic amine, such as morpholine. A buffer may be a known buffer such as
sodium
carbonate, potassium carbonate, sodium phosphate, sodium hydrogen phosphate,
and sodium
dihydrogen phosphate.
[00085] A fatty amine may be any fatty amine known by a person skilled in the
art. An
alkoxylated fatty amine is derived from the respective fatty amine, wherein
the respective
alkoxylated compound is preferably an ethoxylated compound containing one or
more
fragments derived from ethylene oxide (EO-fragment). The respective fatty
amine or
alkoxylated fatty amine may be a primary, secondary or tertiary amine. The
(alkoxylated)
fatty amine contains at least one substituent, which is a saturated or
unsaturated, branched or
linear alkyl group having between 8 to 22 carbon atoms (C8-C22). The
(alkoxylated) fatty
amine may also be a mixture of two or more (alkoxylated) fatty amines
according to said
definition.
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WO 2009/120751 21 PCT/US2009/038196
[00086] Preferably, a fatty amine is a compound according to formula (III)
R
(III)
N -R -X
R 2'
[00087] wherein R1 is an alkyl group having between 8 to 30 carbon atoms, and
W is a
hydrogen, alkyl group or hydroxyalkyl group having 1 to 4 carbon atoms, R3 is
hydrogen or
an alkylene group having from 2 to 12 carbon atoms, and X (if R3 is not H) is
a hydrogen or a
hydrophilic group such as -NH2, -OR4, -S03-(amine alkoxylate), amine
alkoxylate or
alkoxylate, and R4 ist hydrogen or (Cl - C18)-alkyl.
[00088] Preferred alkoxylated fatty amines are derived from the compounds
according to
formula (III), whereby the respective compounds additionally contain one or
more
alkoxylate-fragments, preferably one or more fragments derived from ethylene
oxide
(ethoxylate-fragment or EO-fragment), more preferably 1 to 40 and most
preferably 5 to 25
fragments derived from ethylene oxide. The respective alkoxylate-fragments may
be
contained within any substituent R1..R3, preferably within substituent-Rl
[00089] A fatty mine oxide or an alkoxylated fatty amine oxide may be any
compound
derived from the above-indicated fatty amines or alkoxylated fatty amines,
respectively,
which are tertiary amines additionally having an oxygen atom bound to the
(tertiary) nitrogen
atom.
[00090] Examples of fatty amines (X or R3 = H) are: dimethyl decyl amine,
dimethyl
octyl amine, octyl amine, nonyl amine, decyl amine, ethyl octyl amine and
mixture thereof
[00091] When X is -NH?, preferable examples are alkyl propylene amines such as
N-coco-
1,3-diaminopropane, N-oleyl-1,3-diaminopropane, N-tallow-1,3-diaminopropane or
mixtures
thereof
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WO 2009/120751 22 PCT/US2009/038196
[00092] Examples of preferable ethoxylated amines are ethoxylated tallow
amine,
ethoxylated coconut amine such as cocoamine ethoxylates with 1-30 EO-
fragments, which
are commercially available, for example, as Ethomeen C 15 or Ethomeen C25
(Akzo Nobel),
ethoxylated alkyl propylene amines and mixtures thereof.
[00093] Examples of fatty mine oxides are tallow bis-(2-hydroxyethyl-)amine
oxide, C14-
alkyl (dimethyl) amine oxide, (C12-C14) alkyl (dimethyl) amine oxide and
mixtures thereof.
[00094] More preferably, the base (component a) is at least one compound
selected from
an alkanol amine, ammonia hydroxide, alkali hydroxide, urea, sodium carbonate,
potassium
carbonate, a fatty amine according to formula (III), wherein X is -NH2 or a
fatty mine oxide
according to general formula (III), wherein X is H and which is a tertiary
amine additionally
having an oxygen atom bound to the nitrogen atom.
1000951 Even more preferably, the base (component a) is at least one compound
selected
from an alkonol amine, ammonium hydroxide, potassium hydroxide, or sodium
hydroxide.
Most preferably, the base is monoethanole amine (MEA), diethanole amine (DEA)
or
triethano_e amine (TEA).
[00096] The liquid composition contains -component a) in an amount of at-least
2 wt.-%,
preferably in an amount of 2 to 25 wt.-%, more preferably in an amount of 4 to
20 wt.-% and
most preferably in an amount of 4 to 15 wt.-%.
[000971 The liquid composition (employed in step b) contains as component b)
at least one
fatty acid. The fatty acid may be any fatty acid known to the skilled person.
Preferably, the
fatty acid is a C8-C22-fatty acid such as capric acid, Iauric acid, myristic
acid, palmitic acid,
stearic acid, oleic acid or linoleic acid.. The fatty acid may he a saturated
fatty acid, a mono-
unsaturated fatty acid or a polyunsaturated fatty acid and mixtures thereof.
Most preferably,
the fatty acid is oleic acid.
[00098] Due to the pH-value of the liquid composition employed in step b) of
the present
invention, the fatty acid (component b) is usually completely or at least
partially present in its
unprotonated form within said liquid composition. However, the respective
fatty acid may be
employed in its free form when preparing the liquid composition. The base
(component a)
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and the fatty acid (component b) usually undergo a chemical reaction and/or
form an adduct
with each other. The reaction product and/or adduct of the base and the fatty
acid can be
considered as a soap, which means that the fatty acid employed is completely
or at least
partially transferred into a corresponding salt.
[00099] The liquid composition contains component b) in an amount of at least
2 wL-%,
preferably in an amount of 2 to 30 wt.-%, more preferably in an amount of 5 to
25 wt.-% and
most preferably in an amount of 8 to 20 wt.-%.
[000100] The liquid composition employed in step b) of the present invention
has a pH-value
in a range of > 5, more preferably in the range of > 7, in particular in the
range of 9 to 13.
[000101] Within the liquid composition employed in step b) of the present
invention,
component a) (the base) and component b) (fatty acid) may be present at any
ratio to each
other under the proviso that the pH-value of the liquid composition is in the
range of > 5.
Examples of molar ratios of the base versus the fatty acid are 0.63: 1, 2.4 :
1, 4.0 : 1 or even
25.0: 1. Preferably, the liquid composition contains a molar excess of the
base versus the
fatty acid. More preferably, the molar ratio of the base versus the fatty acid
is in the range of
2.0: 1 to 4.5 : 1 [mol/mol].
[000102] In an embodiment of the present invention, the liquid composition
employed in
step b) additionally contains water. Preferably, water is employed as a
balance, which means
that water is added in an amount of 100 wt.-% minus the sum of the residual
components of
the respective liquid composition. If present, the concentration of water in
the liquid
composition is in an amount of 0.1 to 96 wt.-%, more preferably in an amount
of 20 to 90
wt.-%, most preferably in an amount of 40 to 80 wt.-%.
1000103] Besides the base, the fatty acid and optionally water, the liquid
composition
employed in step b) may contain one or more further components such as
surfactants,
emulsifiers, solvents, hydrotropes, corrosion inhibitors, stress-cracking
inhibiting agents,
coupling agents, anti-wear agents, antimicrobial agents, friction or viscosity
modifiers, anti-
foaming agents or chelating agents. The optional components are chosen in a
way, that they
provide a pH-value of the liquid composition in the range of > 5 when mixed
together.
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WO 2009/120751 24 PCT/US2009/038196
1000104] The liquid composition may contain a chelating agent in one
embodiment. In
particular, such chelating agents are ethylene diamine tetraacetic acid (EDTA)
or salts
thereof, in particular disodium or tetrasodium salt, iminodisuccinic acid
sodium salt, trans-
1,2-diaminocyclohexane tetracetic acid monohydrate, diethylene triamine
pentacetic acid,
sodium salt of nitrilotriacetic acid, pentasodium salt of N-hydroxyethylene
diamine
triacetic acid, trisodium salt of N,N-di(beta-hydroxyethyl)glycine, or sodium
salt of sodium
glucoheptonate.
[000105] In one embodiment, the liquid composition may further contain at
least one
hydrotrope. Hydrotropes are known to a person skilled in the art and
disclosed, for example,
in EP-B 1 444 316 or US-A 4,604,220. Preferably, the hydrotrope is an anionic
sulfonate
such as the alkali metal salts of C6-C18 alkaryl sulfonates such as 1-octane
sulfonate, the
alkali metal aryl sulfonates, C6-C30 alkaryl sulfonates such as the sodium C2-
C18 alkyl
naphthalene sulfonates, sodium xylene sulfonates, sodium cumene sulfonates,
alkyl benzene
sulfonates or allcylated diphenyl oxide disulfonates. More preferably, the
hydrotrope is the
sodium salt of xylene sulfonic acid or the sodium salt of cumene sulfonic
acid.
10001061 In another embodiment, the liquid composition may further contain at
least one
stress-cracking inhibiting agent (stress-cracking inhibitor). Preferably, the
stress-cracking
inhibiting agent is an alkyl phosphate ester or an alkyl aryl phosphate ester.
Further suitable
stress-cracking inhibiting agents are selected from polyoxyethylene decyl
ether phosphoric
acid or the potassium salt thereof, polyoxyethylene nonyiphenyl ether
phosphoric acid or the
potassium salt thereof, polyoxyethylene dinonylphenyl ether phosphoric acid or
the
potassium salt thereof, and mixtures thereof.
[000107] In another embodiment, the liquid composition may further contain at
least one
corrosion inhibitor as defined under step a).
[000108] If present, the liquid composition contains the chelating agent, the
hydrotrope, the
corrosion inhibitor or the stress-cracking inhibiting agent each in an amount
of < 30 wt.-%,
more preferably in an amount of 10-30 wt.-%, most preferably in an amount of
15-25 wt.-%.
However, if the liquid composition contains at least three components selected
from the
chelating agent, the hydrotrope, the corrosion inhibitor and the stress-
cracking inhibiting agent,
the sum of the respective individual amounts of all components is preferably <
40 wt.-%.
CA 02719568 2010-09-23
WO 2009/120751 25 PCT/US2009/038196
[000109] In one embodiment of the present invention, a liquid composition is
employed
containing 4 to 20 wt.-% of at least one base, 5 to 25 wt.-% of at least one
fatty acid, 40 to 80
wt.-% of water and 0 to 30 wt.-% of at least one chelating agent, at least one
hydrotrope, at
least one corrosion inhibitor, and/or at least one stress-cracking inhibitor.
Preferably, the base
is present in a molar excess versus the fatty acid.
10001101 The liquid composition employed in step b) may be prepared as known
in the art,
for example, by mixing the individual components in any order.
[000111] Operation mode of steps a) and/or b)
[000112] The method according to the present invention can be employed on any
conventional conveyor belt systems (units) known to a person skilled in the
art. The conveyor
belt system, in particular the chains and tracks, may be partially or
completely made of any
material known in the art such as steel, in particular stainless steel, or
plastic. Such conveyor
belt (installations) are widely used for example in the food and/or beverage
industry, for
example, for the cleaning, filling or refilling of containers such as bottles.
Usually, a
conveyor belt system contains several individual conveyor belts (conveyor belt
sections).
10001131 -The object to be transported-on the respective conveyor belt maybe
any object
known by a skilled person to be employed in this respect, such as containers,
in particular
bottles, cans or cardboards. Said object may be partially or completely made
of any material
such as metal, glass, carton or plastic, preferably made of glass or plastic.
Preferred plastic
articles or containers are made of polyethylene terephthalate (PET),
polyethylene naphthalate
(PEN), polycarbonate (PC) or polyvinylchloride (PVC).
[000114] In one embodiment of the present invention the conveyor belt is
partially or
completely made of steel, in particular stainless steel, and/or the object
transported on the
conveyor belt is partially or completely made of glass, in particular a glass
bottle. This
embodiment of the present invention is preferably employed in a process for
filling and in
particular for refilling such objects.
[000115] In the method according to the present invention, the lubricant
concentrate
employed as a dry lubricant in step a) may be applied onto the respective
conveyor belt by
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any method known in the state of the art. WO 01/07544 provides an overview of
potential
ways of applying the lubricant concentrate onto the (upper) surface of the
conveyor belt. As
an applicator a spray nozzle, a metered diaphragm pump, a brush applicator or
a so-called
flicker may be employed. The lubricant concentrate may be applied continuously
or
preferably discontinuously. For example, the lubricant concentrate may be
discontinuously
applied onto the conveyor belts surface every five minutes, twenty minutes or
even every 24
hours, depending on the objects to be transported.
[000116] The liquid composition employed in step b) of the present invention
can be
applied to the surface of the conveyer belt by any method known in the state
of the art.
Usually, the liquid composition is carried out in a way which corresponds to a
wet lubrication
(process). This means that the liquid composition as described above is
preferably diluted to a
"use solution (of the liquid composition)". Usually, the use solution of the
liquid composition
is obtained by diluting the respective liquid composition with a solvent,
preferably with
water. The dilution factor is usually in the range of 50 to 500, preferably in
the range of 80 to
150, most preferably (about) 100.
[000117] By consequence, the use solution contains the individual compounds of
the liquid
composition as described above in an amount, which equals the ordinary,
preferred, more
preferred or even most preferred amount of the respective -component divided
by the dilution
factor. For example, a use solution with a dilution factor of 100 contains
component a) in an
amount of at least 0.02 wt.-%, preferably in an amount of 0.02 to 0.25 wt.-%,
more preferably
in an amount of 0.04 to 0.2 wt.-% and most preferably in an amount of 0.04 to
0.15 wt.-%.
[000118] In one embodiment of the present invention a use solution of the
liquid
composition is employed in step b) containing i) at least 0.02 wt.-%, more
preferably 0.04 to
0.2 wt.-% of at least one base, ii) at least 0.02 wt.-%, more preferably 0.05
to 0.25 wt.-% of at
least one fatty acid, iii) 0 to 0.3 wt.-%, more preferably 0 to 0.25 wt.-% of
at least one
chelating agent, at least one hydrotrope, at least one corrosion inhibitor
and/or at least one
stress-cracking inhibitor and iv) at least 50 wt.-%, more preferably at least
95 wt.-% of at
least one solvent, preferably water. Preferably, the base is present in a
molar excess versus
the fatty acid.
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[000119] This means further that the liquid composition or the use solution
thereof is
applied to the surface of the conveyer belt in a way, that a significant
amount of the liquid
composition flows off from the surface of the respective conveyer belt.
Preferably, at least
30% of volume of the applied amount of liquid flows off, more preferably at
least 50% by
volume, in particular at least 90% by volume. Preferably, the liquid
composition is added at a
ratio of 1.5 to 201/hour on the respective conveyor belt (per conveyor belt
track depending on
ordinary size).
[000120] For example, (the use solution of) the liquid composition of step b)
may be
applied via an automatic dosing system. The typical use concentration is 0.6-
1.2% w/w, (1
part liquid composition to 83-167 parts water), depending on the application,
water hardness
and degree of soiling. Preferably, this is recommended for use where the water
hardness is
less than 185 mg/1 calcium carbonate (maximum tolerance for 1.2% w/w given),
the use of
softened water advised.
[000121] Step b) is carried out to effect a cleaning of the conveyor belt to
remove dirt from
the conveyor belt's surface due to the operator conditions according to step
a). In addition,
step b) according to the present invention also provides a lubrication effect.
Therefore, step b)
is carried out for cleaning and (optionally) lubricating the conveyor belt.
[000122] The liquid composition can be applied to the conveyor belt's surface,
for example,
by a spray nozzle or any other pump known to a skilled person. There is no
limit for the
operation time of carrying out step b). Preferably, the operation time of step
a) exceeds that of
step b), more preferably by a factor of at least 10, much more preferably by a
factor of at least
20, and in particular by a factor of at least 40.
[000123] In one embodiment of the present invention, the method is carried out
continuously, whereby steps a) and b) are carried out in alternate order.
Without any
problems, it is possible to switch between steps a) and b) several times,
whereby the intervals
of operation for steps a) and b) may vary. It is also possible to carry out
step b) only in some
sections of the conveyor belt system.
[000124] In one embodiment, the lubricant concentrate containing at least one
fatty acid is
employed (only) in at least one section of the conveyor belt (system) as a dry
lubricant within
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step a) of the method according to the present invention. In this embodiment a
use solution of
a lubricant is employed as a wet lubricant in the remaining (at least one)
sections of the same
conveyor belt (system). Preferably, the use solution of a lubricant employed
as a wet
lubricant in the remaining sections of the conveyor belt is made from a
lubricant concentrate
containing at least one fatty acid and optionally a corrosion inhibitor. More
preferably, the
lubricant concentrate to be employed as dry lubricant and the use solution of
a lubricant
employed as a wet lubricant are made from the same lubricant concentrate.
[000125] In another embodiment of the present invention, a rinse step (washing
step) with
water is temporarily carried out in addition to step b) on (or for) at least
one or even all of the
individual sections of the conveyor belt (system), onto which a lubricant
concentrate is
applied as a dry lubricant. The rinse step is carried out for a certain period
of time, preferably
for 10 up to 30 minutes. Afterwards, the lubricant concentrate containing at
least one fatty
acid can again be applied onto the respective conveyor belt (sections) as a
dry lubricant
without (significantly) interrupting or disturbing the transportation of the
objects such as
glass bottles.
[000126] Said embodiments are preferably employed in transportation of objects
on
conveyor belts, whereby the conveyor belt is integrated into different
operation units
(sections) to carry out for example bottle washing, sorting, filling,
labelling or packaging
steps. Preferably, said embodiments are employed in the process of filling or
refilling of glass
containers, in particular glass bottles, in particular on a conveyor belt
partially or completely
made of steel, preferably stainless steel.
[000127] Preferably, the individual sections of the conveyor belt may be
integrated into,
connected with or placed in between a depelletizer, a bottle sorting unit, a
bottle washer, a
filler unit, a capping unit, a labelling unit, a packaging unit (area), a
crate conveyor unit
and/or an area for electronic bottle inspections. The respective sections
(units) may be
connected with each other in any order and/or number.
[000128] More preferably, the temporary rinse step or the wet lubrication
according to the
above embodiments are carried out or employed between a depelletizer (unit)
and a bottle
washer, a depelletizer and a bottle sorting unit, a bottle sorting unit and a
bottle washer and/or
a filling unit and a labelling unit.
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[000129] In another embodiment of the present invention, step a) of the method
of
lubricating a conveyor belt is carried out in respect of the lubrication of
the respective
conveyor belt system employing a lubricant concentrate containing at least one
fatty acid as a
dry lubricant in a dry lubrication process which is temporarily combined with
a wet
lubrication of the respective conveyor belt employing a use solution of a
lubricant. The use
solution is preferably a use solution of a lubricant concentrate containing at
least one fatty
acid. The temporary wet lubrication can be carried out on the entire conveyor
belt (system) or
only in parts thereof (sections).
[000130] The following examples serve to present a more detailed explanation
of the
invention.
[000131] Examples
[000132] In the following, all percent (%)-volumes of components of
compositions are
expressed as percent-by-weight (wt.-%) unless indicated otherwise.
1000133] Example I Dry Lubrication According to Step a)
[000134] 1 Track Conveyor Testing
[0001351 1.1 Description of Test Method Lubricity and Durability
[000136] 1.1.1 Test Track
[000137] The trials are carried out on a pilot conveyor facility. This pilot
conveyor contains
stainless steel and plastic (Acetal) test tracks.
[000138] 1.1.2 Test Procedure
10001391 The following standard test procedure is applied:
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[000140] 1. Prior doing any trials, ensure that the test track is free of
residues. If
necessary, clean the track with an acidic or alkaline cleaner and/or with
alcohol to remove any traces of lubricants from the previous trial.
[000141] 2. Rinse the track with water (approx. 10 min) and dry it with
Kleenex.
[000142] 3_ Start the program for the digital track conveyor system.
[000143] 4. After 2 min: pipette 10 ml of the respective composition directly
on the
chain. This process has to be done very carefully and slowly to ensure, that
the
whole chain surface is being treated. Use a plastic cloth or a brush to
support
spreading.
[000144] 5. After 20 min from start: switch on the tap water flush (approx. 8
ltr./min.).
[000145] 6. After 10 min rinsing: stop program
10001461 1.2 Evaluation
[000147] During the trial, 6-8 bottles are placed on the test track. The
pulling power
(Fz) is constantly measured via an electronic scales with A/D converter. The
measurement is
limited to a maximum of 2 kg. The coefficient pulling power/weight of bottles
or cans
represents the friction coefficient which expresses the lubricity (. = FZ/FN).
This data is finally
transferred to MS Excel and the values (v.) can be read out in the middle of
the lubricant to
unfavourable conditions such as heavy loading or water wash off.
[000148] 2. Trials
[000149] 2.1. Glass bottles on Stainless steel tracks
[000150] Tests are carried out with 8 glass bottles with a total weight of 8,1
kg.
[000151] 2.1.1. Concentrate compositions according to the state of the art
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[000152] A concentrate of a lubricant 1 is prepared, containing 3,68% N-oleyl-
l,3-
diamnupropane, 3,6% (C16_18) alkyl (9EO) carboxylic acid and 6% polyethylene
glycol
(M=200) added up with softened water to 100%. 5% of this lubricant 1 diluted
with 95% H2O
is used as concentrate A and 95% of this lubricant 1 diluted with 5% H2O is
used as
concentrate B.
[000153] Oil in water emulsions are prepared (listed below) by shaking the
ingredients in
small 20 ml screw top glasses.
Concentrate C: 50% silicone oil (Dow Coming 200) and 50% H2O
Concentrate D: 95% sunflower oil and 5% H2O
Concentrate E: 75% mineral oil and 25% H2O
[000154] 2.1.2. Concentrate compositions according to the present invention
[000155] Concentrates I and 2 contain oleic acid as (free) fatty acid. A
concentrate of a
lubricant 2 is prepared containing 33% oleyl-O-3EO-phosphate ester, 4% (C16-
C18)-alkyl-
5E0-carboxylic acid, 33% (C16-C1S)-alkyl-2EO-carboxylic acid, 13% oleic acid,
8% cetyl
alcohol (1-hexadecanol) and 9% (C4-C8)-alkyl-8E0-carboxylic acid.
Concentrate 1: 8% of lubricant 2 and 92% H2O (pH-value of 2.1)
Concentrate 2: 100% of lubricant 2
Concentrate 3: 5% of oleic acid and 95% dipropylene glycolnmethyl ether
[000156] 2.1.3. Results
[000157] Table 1 below shows friction coefficients (p) at different time
stages. As the
application of lubricant starts after 2 min. the values at 10 and 20 min. show
lubricity. The
water flush starts after 20 min, so 25 min and 30 min are indicators for the
durability. Values
(p) >0,15 show insufficient lubricity and exceeds the measurement device
limit.
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Table 1
Concentrate 0 min. 10 min. 20 min. 25 min. 30 min.
A 0,2 0,20 0,20 >0,25 >0,25
B 0,23 0,125 0,10 >0,25 >0,25
C 0,22 0,135 0,14 0,14 0,185
D 0,20 0,10 0,10 0,11 0,2
E 0,20 0,09 0,09 0,11 0,2
1 0,25 0,09 0,09 0,12 0,14
2 0,20 0,08 0,07 0,13 0,14
3 0,23 0,10 0,10 0,10 0,13
[000158] The concentrates of the invention (Ito 3) show in most cases a
significant
decrease of friction compared to prior art (A - E), when employed in an dry
lubrication
process according to step a) of the present invention. In addition, an
improved performance is
noticed with concentrates 1 to 2 because of longer remaining lubricity during
the wash off
(rinse step starting after 20 min).
[000159] 3. Blackening
Table 2
concentrate Degree- of Blackeming
1 2
2 2
3 4
[000160] Blackening is estimated on a scale from 1 to 5 with some concentrates
as indicated
above under item 2.1, wherein 1 means no Blackening and 5 means unacceptable.
For a
visual assessment lubricant concentrates are applied and the conveyor runs for
30 min with
fixed glass bottles. After the run the bottom of the bottles are wiped with
tissues and the
degree of blackening on the tissues is rated. These experiments show that
blackening is a
serious problem occurring in a dry-lubrication process.
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[000161] Example II Cleaning According to Step b)
Table 3
ste b)
concentration concentration
components in use
in liquid cleaning pH use
use solution of liquid composition solution [Wt.-
composition [wt.- ] %] / dilution
factor
1 KOH 1,00 0,10 / 10 2 97 46
oleic acid 8,00 0,80 / 10
2 NH40H 12,50 0,25150 1 10,25
3 NH4OH 12,50 0,25 / 50 1 10,4
oleic acid 4,00 0,08 / 50
4 TEA 10,00 0,10 / 100 1 9,60
TEA 10,00 0,10 / 100 2 8,26
oleic accid 8,00 0,08 / 100
6 mo holin 10,00 0,10 / 100 2 10,30
7 mo holin 10,00 0,10 / 100 2 9,48
oleic acid 8,00 0,08 / 100
TEA = Triethanolamine
[000162] All cleaning trials are performed with stainless steel plates
(1.4301). 2 drops of a
test solution simulating soil are applied equally on each plate. The test
solution is prepared
using a mixture of 5 g concentrate 2 (see example I item 2.1.2 above) and 0,2
g activated
carbon (simulating the blackening caused by dirt or wear of objects to be
transported on the
conveyor belt). The plates are partially soaked into the use solution
indicated in Table 3. The
use solutions are obtained from the respective liquid composition by dilution
with water at
the factor indicated. The liquid compositions are obtained by mixing the
individual
components as indicated, the balance (total of 100 wt.-%) is obtained by
addition of water.
[000163] The contact time in the use solution is 20 min. without stirring.
Before inspection
all plates are removed from the solutions and allowed to dry at ambient
temperature. After
this procedure the dried plates are evaluated for remaining soil and free
metal surface.
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[000164] Cleaning results are estimated on a scale from I to 5, wherein I
means clean
surface without any residues and 5 means unacceptable cleaning results. It can
be seen from
Table 3 that liquid compositions containing a base and a fatty acid have
identical or very
similar cleaning properties as liquid compositions of the prior art (see, for
example, use
solutions 3 and 2 or 7 and 6).
[0001651 Example1II. Combination of Dry Lubrication and the Cleaning According
to Steps a) and b)
[000166] The following standard test procedure is applied:
[000167] 1. doing any trials, ensure that the test track is free of residues.
If necessary,
clean the track with an acidic cleaner and/or with alcohol to remove any
traces
of lubricants from the previous trial.
[000168] 2. Rinse the track with water (approx. 10 min.) and dry it with
Kleenex.
[000169] 3. Start the program for the digital track conveyor system.
[000170] 4. After 2 min.: pipette 10 ml of the concentrate 1 directly on the
chain. This
process has to be done very carefully and slowly to ensure that the whole
chain surface is being treated. Use a plastic cloth or brush to support
spreading.
[000171] 5. After 10 min. from start: switch on permanent dosing of the use
solution
of the liquid composition of step b).
[0001721 6. After 31 min. from start: stop program.
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Table 4
step a) step b) friction coefficients at
use solution 1 8 min. 11 min. 15 min. 20 rain. 30 min.
time
1 0,08 0,12 0,12 0,12 0,12
2 0,08 0,14 0,13 0,14 0,20
3 0,08 0,14 0,13 0,13 0,13
4 0,08 0,17 0,14 0,15 0,21
0,08 0,15 0,14 0,14 0,13
6 0,07 0,13 0,12 0,15 0,17
7 0,07 0,12 0,12 0,12 0,12
[000173] Table 4 shows friction coefficients ( ) at different time stages.
Step a) is carried
out for 10 minutes employing concentrate I and dry lubrication conditions at a
pH-value of
2.1. Unless indicated otherwise, the experiments are carried out in accordance
with example
I, items 1 and 2. After 10 minutes the conditions are switched to cleaning
conditions
according to step b) of the present invention. The use solutions employed in
step b) of table 4
correspond to the use solutions employed in table 3 under example H. The
respective use
solution is continuously sprayed on the conveyor belt at a rate of 5 l/h.
[000174] The experiments of table 4 demonstrate that an improved and stable
lubricity
(lower -values) is obtained by employing in step b) a liquid composition
containing a base
and a fatty according to the present invention (use solutions 1, 3, 5 and 7).
In contrast to that
decreasing lubrication properties are observed (over the time) when employing
the
corresponding cleaning solutions according to the prior art containing only a
base, but no
fatty acid (use solutions 2, 4 and 6). Furthermore, the experiments of table 4
indicate that a
better lubricity is obtained in step a) under dry lubrication conditions
compared to the
cleaning conditions of step b).
[000175] Example IV Alternate Order of Steps a) and b)
[000176] The standard test procedure of Example III is modified for the long-
term trial:
[000177] 1. to 4. see under example III.
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[000178] 5. Additional 5 ml concentrate 1 are added after 30 min. and 55 min.
[000179] 6. After 70 min. from start: switch on permanent dosing of the use
solution
of the liquid composition of step b).
[000180] 7. After 99 min. from start: switch off permanent dosing of the use
solution
of the liquid composition of step b) and switch back to step a).
[000181] 8. Apply 10 ml of the concentrate 1 directly on the chain and apply
additional 5 ml concentrate I at 110 min and 130 min each.
[000182] 9. After 180 min. from start: stop program.
Table 5
long term trial
t (min) friction coefficient dosing
0,07 initial 10 ml concentrate I
25 0,068
step a) 40 0,063 additional 5 ml concentrate 1 at 30 min.
50 0,06
60 0,06 additional 5 ml concentrate at 55 min.
step b) 70 0,135 start of step b) with use solution 5
95 0,123
100 0,11 initial 10 ml concentrate a)
120 0,071 additional 5 ml concentrate 1 at 110 min.
step a)
140 0,065 additional 5 ml concentrate 1 at 130 min.
180 0,061
[000183] Table 5 shows that steps a) and b) can be easily carried out in
alternate order. The
same level of significantly reduced friction (lower -values; improved
lubricity) is obtained
after switching back from the cleaning conditions of step b) to the dry
lubrication conditions
according to step a) of the present invention. The experiment is carried out
in accordance
with the experiments of table 4 (example III) unless indicated otherwise. In
step a)
concentrate 1 at a pH-value of 2.1 (see also example I, item 2) and in step b)
use solution 5
(see also example IT, Table 3) are employed.
